In the context of screening tests, yield is the measure of previously unrecognized disease, diagnosed as the result of screening and brought to treatment. This definition is provided in reference [8].
Understanding the Concept of Yield
Yield quantifies how effective a screening program is at finding new cases of a disease within a population being screened. It goes beyond simply identifying positive tests; it specifically focuses on detecting disease that was unknown before the screening took place and ensuring that these newly diagnosed individuals are subsequently brought to treatment.
Key components implied by this definition include:
- Previously Unrecognized Disease: This means finding cases in individuals who did not know they had the disease, often before they developed symptoms or sought medical attention for it.
- Diagnosed as the Result of Screening: The detection of the disease must directly result from the screening process itself.
- Brought to Treatment: The identified individuals must enter the healthcare system to receive appropriate management or treatment for the diagnosed condition. This step is crucial because simply finding disease without subsequent action doesn't improve health outcomes.
Yield is therefore a critical metric for evaluating the success and public health impact of a screening program. A higher yield generally indicates a more efficient screening process in identifying new, treatable cases within the target population.
Related Metric: Number Needed to Screen (NNS)
Another related metric mentioned in the reference is the Number Needed to Screen (NNS). According to the World Health Organization (WHO), as cited in reference [9], the NNS represents the number of persons that need to undergo screening in order to diagnose a specific disease, like TB (Tuberculosis), among people at-risk. While yield focuses on the number of newly diagnosed cases found, NNS looks at the effort required (the number of people screened) to find one case. Both metrics are important for understanding the efficiency and resource implications of screening programs.
References:
- [8] Definition of Yield in screening tests.
- [9] WHO definition of Number Needed to Screen (NNS) for TB.
